Energy storage is having energy in reserve for future needs. While it takes millions of years to create huge energy stores in the form of coal, oil, natural gas, and uranium, humans are able to quickly manufacture energy stores such as batteries, and to build dams to store the gravitational energy of water. Although batteries and dams are very useful and important storage systems, the amount stored is very small compared to natural stores. These natural energy stores are large, but finite, and it is important to realize that they will not last forever.

The food a person eats is a personal energy store banking on photosynthesis. In photosynthesis, gaseous carbon dioxide, liquid water, and solar energy interact to produce solid carbohydrates, such as sugar and starch, and gaseous oxygen.

carbon dioxide + oxygen + solar energy → carbohydrates + oxygen

Solar energy for photosynthesis is converted and stored in the molecular...